Driving along about 70MPH and the engine power just died.
Steering wheel still functioned(which it shouldn't if I lost power)
Glow plugs work and engine turns over but it won't start
Had to have it towed to a garage.They can't find the problem diagnostically because the engine won't run.
Sounds electric to me....maybe a sensor?
thanks
Tom

The steering will still work if the engine dies, but you won't have power assist..
What year 7.3? Mileage etc..
Any check engine light prior to the stall?

There's actually quite a few things they can/should check diagnostically for a no start condition with a capable scan tool. Or that the scan tool can actually communicate, or any stored codes that may exist and point to a direction to go. As well as basically looking for some needed system values for a start/run condition. HPOP pressure being one, as well as a few other items can be checked/viewed without an engine run.

With no CEL prior (?), on a stall, fuel delivery may be suspect and should be confirmed, a few system start parameters being met, and the possibility of a electrical/component fail issue,, but the causes for a stall can be many..

First,, Do you hear the Fuel Pump Module 'run sound' when the key is cycled On? Module is frame mounted under about where the driver sits..